全文获取类型
收费全文 | 2325篇 |
免费 | 208篇 |
专业分类
电工技术 | 21篇 |
综合类 | 29篇 |
化学工业 | 912篇 |
金属工艺 | 26篇 |
机械仪表 | 44篇 |
建筑科学 | 99篇 |
矿业工程 | 6篇 |
能源动力 | 55篇 |
轻工业 | 379篇 |
水利工程 | 41篇 |
石油天然气 | 4篇 |
无线电 | 83篇 |
一般工业技术 | 376篇 |
冶金工业 | 149篇 |
原子能技术 | 8篇 |
自动化技术 | 301篇 |
出版年
2024年 | 15篇 |
2023年 | 22篇 |
2022年 | 124篇 |
2021年 | 177篇 |
2020年 | 97篇 |
2019年 | 85篇 |
2018年 | 90篇 |
2017年 | 96篇 |
2016年 | 109篇 |
2015年 | 92篇 |
2014年 | 124篇 |
2013年 | 173篇 |
2012年 | 141篇 |
2011年 | 203篇 |
2010年 | 120篇 |
2009年 | 118篇 |
2008年 | 127篇 |
2007年 | 99篇 |
2006年 | 70篇 |
2005年 | 49篇 |
2004年 | 46篇 |
2003年 | 49篇 |
2002年 | 41篇 |
2001年 | 25篇 |
2000年 | 28篇 |
1999年 | 28篇 |
1998年 | 34篇 |
1997年 | 21篇 |
1996年 | 14篇 |
1995年 | 17篇 |
1994年 | 19篇 |
1993年 | 15篇 |
1992年 | 7篇 |
1991年 | 9篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 6篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1964年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有2533条查询结果,搜索用时 31 毫秒
991.
Claudia Rode Annika Schmidt Ralf Wyrwa Jürgen Weisser Kathrin Schmidt Norbert Moszner Ralf‐Peter Gottlöber Klaus Heinemann Matthias Schnabelrauch 《Polymer International》2014,63(9):1732-1740
Radiopaque biodegradable polymers have been synthesized by ring‐opening polymerization of l /dl ‐lactide and caprolactone with the iodine‐containing starter molecule 2,2‐bis(hydroxymethyl)propane‐1,3‐diyl bis(2,3,5‐triiodobenzoate) followed by chain elongation with a diacid chloride or diisocyanates. The resulting polyesters and poly(ester‐urethanes) exhibited a radiopacity of 60?124% relative to an aluminium sample of the same thickness. The polymers were processed into monofilament fibres by melt‐spinning and into fibre meshes by electrospinning. All polymers were biodegradable in simulated body fluid medium under in vitro conditions and showed an excellent in vitro cytocompatibility even after several months of hydrolytic degradation. A current drawback is the relatively low tensile strength of the polymer monofilaments, which needs to be improved for applications as textile structures. Nevertheless, the new radiopaque and biodegradable polymers are promising candidates in fields of application where radiopacity of implants is an important parameter. 相似文献
992.
Alumina coating with TiO2 and its effect on catalytic photodegradation of phenol and p‐cresol
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
993.
Andrés Schlageter-Tello Eddie A.M. Bokkers Peter W.G. Groot Koerkamp Tom Van Hertem Stefano Viazzi Carlos E.B. Romanini Ilan Halachmi Claudia Bahr Daniël Berckmans Kees Lokhorst 《Journal of dairy science》2014
Locomotion scores are used for lameness detection in dairy cows. In research, locomotion scores with 5 levels are used most often. Analysis of scores, however, is done after transformation of the original 5-level scale into a 4-, 3-, or 2-level scale to improve reliability and agreement. The objective of this study was to evaluate different ways of merging levels to optimize resolution, reliability, and agreement of locomotion scores for dairy cows. Locomotion scoring was done by using a 5-level scale and 10 experienced raters in 2 different scoring sessions from videos from 58 cows. Intra- and interrater reliability and agreement were calculated as weighted kappa coefficient (κw) and percentage of agreement (PA), respectively. Overall intra- and interrater reliability and agreement and specific intra- and interrater agreement were determined for the 5-level scale and after transformation into 4-, 3-, and 2-level scales by merging different combinations of adjacent levels. Intrarater reliability (κw) ranged from 0.63 to 0.86, whereas intrarater agreement (PA) ranged from 60.3 to 82.8% for the 5-level scale. Interrater κw = 0.28 to 0.84 and interrater PA = 22.6 to 81.8% for the 5-level scale. The specific intrarater agreement was 76.4% for locomotion level 1, 68.5% for level 2, 65% for level 3, 77.2% for level 4, and 80% for level 5. Specific interrater agreement was 64.7% for locomotion level 1, 57.5% for level 2, 50.8% for level 3, 60% for level 4, and 45.2% for level 5. Specific intra- and interrater agreement suggested that levels 2 and 3 were more difficult to score consistently compared with other levels in the 5-level scale. The acceptance threshold for overall intra- and interrater reliability (κw and κ ≥0.6) and agreement (PA ≥75%) and specific intra- and interrater agreement (≥75% for all levels within locomotion score) was exceeded only for the 2-level scale when the 5 levels were merged as (12)(345) or (123)(45). In conclusion, when locomotion scoring is performed by experienced raters without further training together, the lowest specific intra- and interrater agreement was obtained in levels 2 and 3 of the 5-level scale. Acceptance thresholds for overall intra- and interrater reliability and agreement and specific intra- and interrater agreement were exceeded only in the 2-level scale. 相似文献
994.
995.
996.
Claudia M. Berlanga-Reyes Elizabeth Carvajal-Millan Kevin B. Hicks Madhav P. Yadav Agustín Rascón-Chu Jaime Lizardi-Mendoza Alma R. Toledo-Guillén Alma R. Islas-Rubio 《International journal of molecular sciences》2014,15(10):19106-19118
Wheat bran arabinoxylan (WBAX) gels entrapping standard model proteins at different mass ratios were formed. The entrapment of protein affected the gel elasticity and viscosity values, which decreased from 177 to 138 Pa. The presence of protein did not modify the covalent cross-links content of the gel. The distribution of protein through the network was investigated by confocal laser scanning microscopy. In mixed gels, protein aggregates forming clusters were detected at protein/polysaccharide ratios higher than 0.25. These clusters were not homogeneously distributed, suggesting that WBAX and protein are located in two different phases. The apparent diffusion coefficient (Dm) of proteins during release from mixed gels was investigated for mass ratios of 0.06 and 0.12. For insulin, Dm increased significantly from 2.64 × 10−7 to 3.20 × 10−7 cm2/s as the mass ratio augmented from 0.06 to 0.12. No significant difference was found for Dm values of ovalbumin and bovine serum albumin released from the mixed gels. The results indicate that homogeneous protein/WBAX gels can be formed at low mass ratios, allowing the estimation of Dm by using an analytical solution of the second Fick’s law. 相似文献
997.
Solvent extraction is a critical step in many industrial mineral‐processing circuits and is affected by chemical (e.g., metal ions, extractant, pH, reaction rate) and physical (e.g., interfacial phenomena, mass transport, temperature) factors. Here, a new type of microfluidic contactor is presented that enables higher volumetric throughputs and straightforward counter‐current operation compared with Y‐Y chips. A single chip design can handle a wide range of organic/aqueous phase ratios, thereby enabling stable operation for non‐ideal solutions and fluctuating flow. An expression defining this widened operational window has been derived based on the relative stream geometries and liquid viscosities. A two‐stage counter‐current circuit is demonstrated for the extraction of platinum(IV) chloride. 相似文献
998.
Selenobaldo A. C. de Sant-Anna Claudia P. Jantalia Jerusa M. Sá Lourival Vilela Robélio L. Marchão Bruno J. R. Alves Segundo Urquiaga Robert M. Boddey 《Nutrient Cycling in Agroecosystems》2017,108(1):101-120
In Brazil’s central savanna region, government policy is to encourage the conversion of conventional plough tillage (PT) agriculture to no-till (NT) and raise the productivity of under-utilized pastures, including their conversion to integrated crop-livestock (ICL) systems, with the objective of increasing soil organic carbon (SOC) at the expense of atmospheric carbon dioxide. An experiment was established in 1991 by liming and fertilizing at two levels an area of native vegetation (NV). The treatments, replicated in randomized plots, included pastures, continuous cropping and ICL systems under PT or NT. The aim of this study was to quantify the SOC accumulation to 100 cm depth under these treatments over time. The high C:N ratios suggested that there was a high proportion of charcoal present in the soil. Increasing fertilizer inputs had no overall significant effect on SOC stocks. Stocks of SOC changed little under pastures. Analyses of 13C abundance showed that higher fertilizer inputs increased the decomposition rate of C derived from NV under pure grass pastures. Continuous cropping under NT preserved SOC and under PT there were significant losses. The highest SOC stocks were found under ILP treatments, but not all ILP treatments accumulated SOC even under NT. These results indicate that government initiatives to substitute PT with NT and to intensify beef cattle production will have only modest short-term gains in SOC accumulation. 相似文献
999.
Claudia Fösleitner Carmen Sommer Philipp Berglez Jürgen Seybold Klaus Aichhorn 《e & i Elektrotechnik und Informationstechnik》2014,131(1):21-25
Nowadays, it is impossible to imagine daily life without satellite communication and satellite navigation. Many applications and services use communication and satellite navigation technologies in order to facilitate daily life. This article focuses on location-based services (LBS) provided by TeleConsult Austria which can be used in different fields and circumstances. These services contribute significantly to personal security and increased mobility. 相似文献
1000.
Claudia V. Goldman Dan Gang Jeffrey S. Rosenschein Daniel Lehmann 《Annals of Mathematics and Artificial Intelligence》1999,25(1-2):69-90
The system presented here shows the feasibility of modeling the knowledge involved in a complex musical activity by integrating
sub-symbolic and symbolic processes. This research focuses on the question of whether there is any advantage in integrating
a neural network together with a distributed artificial intelligence approach within the music domain. The primary purpose
of our work is to design a model that describes the different aspects a user might be interested in considering when involved
in a musical activity. The approach we suggest in this work enables the musician to encode his knowledge, intuitions, and
aesthetic taste into different modules. The system captures these aspects by computing and applying three distinct functions:
rules, fuzzy concepts, and learning. As a case study, we began experimenting with first species two-part counterpoint melodies.
We have developed a hybrid system composed of a connectionist module and an agent-based module to combine the sub-symbolic
and symbolic levels to achieve this task. The technique presented here to represent musical knowledge constitutes a new approach
for composing polyphonic music.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献